The only case where w is not a factor is when the applied voltage is DC. With AC applied, the capacitors become reactive, where Xc = 1/wc. That makes both capacitors appera as if they were resistive elements in parallel with the resistors.

For two resistors in parallel, the product of the resistances over the sum of the resistances will give the equivalent resistance. Use Xc as the value of one resistor, and you get the answer.